This invention relates, in general, to aircraft flight instrumentation and, more particularly, to apparatus for providing a display of a cluster of instruments that is positioned directly in front of the pilot and which provide him with the primary flight guidance information necessary to control an aircraft through its entire flight regime from takeoff to landing.
The prior art equipment used for primary flight data comprises ten dedicated instruments which are typically spread over a panel area that is approximately 16 inches wide by 13 inches high and requires the pilot to cover a visual scan radius of 10 inches from the center of the attitude-director indicator to cover the multitude of information which is competing for his attention. This wide scan area and excess of extraneous information is particularly distracting during a landing maneuver under low visibility conditions when only a limited number of key parameters are necessary and should be very readily apparent to be effective during this critical maneuver.
The present invention utilizes the digital raster cellular CRT technique disclosed in U.S. Pat. No. 4,070,662, entitled "Digital Raster Display Generator for Moving Displays", invented by P. L. Narveson and assigned to the Sperry Rand Corporation who is also the assignee of the present invention. Said Ser. No. 630,833 issued on Jan. 24, 1978 as U.S. Pat. No. 4,070,662 which is considered incorporated herein by reference. The cell technique disclosed therein enables all the information on the entire cluster of ten electromechanical instruments to be presented in a clear and concise format on a usable CRT screen size that is typically 6.4 inches wide and 4.8 inches high, achieving a scan radius reduction from 10 inches to four inches and a panel area reduction from 130 square inches to 48 square inches. Only that data necessary for a particular phase of the flight mission need be presented with all other information suppressed until required.
The use of the digital raster CRT writing technique is ideally suited to interface with serial digital bus transmission of data which typically requires only a few wires to convey a multitude of information and therefore lends itself to very efficient switching of information from one source to an alternate source should one source of data become invalid.
Another key capability of the digital raster CRT technique is the assignment of priority of symbology to specific areas of the screen. This minimizes any conflict of data presentation and is particularly effective, for instance, in reducing clutter and eliminating parallax of the flight director command cue presentation that is typical of conventional electromechanical attitude director indicators.
Unique circuits that are disclosed herein relate to overlay of sky-ground shading to display an artificial horizon and apparatus to move symbology smoothly from one cell to an adjacent cell in any direction. Additionally the apparatus is configured to provide unique aircraft displays in a manner to be described.